Two Dimensional Arrays (array2)

Definition

An instance A of the parameterized data type array2<E> is a mapping from a set of pairs I = [a..b] x [c..d], called the index set of A, to the set of variables of data type E, called the element type of A, for two fixed intervals of integers [a..b] and [c..d]. A(i,j) is called the element at position (i,j).

Creation

array2<E>	A(int a, int b, int c, int d);
		creates an instance A of type array2<E> with index set [a..b]x [c..d].
array2<E>	A(int n, int m);	creates an instance A of type array2<E> with index set [0..n-1]x [0..m-1].

Operations

E&	A(int i, int j)	returns A(i,j). Precondition: a<= i<= b and c<= j<= d.
int	A.low1()	returns a.
int	A.high1()	returns b.
int	A.low2()	returns c.
int	A.high2()	returns d.

Implementation

Two dimensional arrays are implemented by C++vectors. All operations take time O(1), the space requirement is O(I* sizeof(E)).